Add forgotten testcase.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176032 91177308-0d34-0410-b5e6-96231b3b80d8

test/CodeGen/split-debug-filename.c

@@ -0,0 +1,7 @@
+// RUN: %clang -target x86_64-linux-gnu -gsplit-dwarf -S -emit-llvm -o - %s | FileCheck %s
+int main (void) {
+  return 0;
+}
+
+// Testing to ensure that the dwo name gets output into the compile unit.
+// CHECK: split-debug-filename.dwo